Moulding Machines — Characteristic of a Diaphragm Moulding Machine What sand hardness/packing profile is produced in a flask when using a diaphragm moulding machine with membrane pressure compaction?

Introduction / Context:
Moulding machines differ in how they compact sand. Jolt, squeeze, jolt-squeeze, sand-slinger, and diaphragm (membrane) machines each create distinctive hardness profiles. Knowing these profiles helps you pick the right machine for dimensional accuracy and surface finish.

Given Data / Assumptions:

• Diaphragm machine uses air pressure acting through a flexible membrane to compact sand.
• Pressure distribution is broad and nearly uniform compared with localized tamping.
• Objective is consistent sand hardness with minimal gradients.

Concept / Approach:
With membrane pressure, the applied load spreads over the mould area, reducing the extreme hardness gradients typical of jolt-only (harder near the pattern plate) or squeeze-only (harder near the squeeze head). The result is a comparatively uniform hardness/packing throughout the depth of the mould, which improves stability and reduces distortion.

Step-by-Step Solution:
Identify compaction mechanism: a flexible diaphragm distributes pressure uniformly.Predict effect: fewer localized peaks; more uniform sand density.Therefore, the correct description is “give uniform sand hardness throughout the mould”.

Verification / Alternative check:
Process comparisons in foundry texts depict diaphragm packing curves as flatter than jolt or squeeze methods.

Why Other Options Are Wrong:
Options A and B describe gradients characteristic of jolt or squeeze processes, not diaphragm.Option C is vague; option D explicitly states uniform hardness and matches diaphragm behavior.

Common Pitfalls:
Assuming all machine moulding gives similar hardness; mechanism matters.

Final Answer:
give uniform sand hardness throughout the mould